diff --git a/src/security/sec-tpm-osx.hpp b/src/security/sec-tpm-osx.hpp
index 1f95cdc..c4a4972 100644
--- a/src/security/sec-tpm-osx.hpp
+++ b/src/security/sec-tpm-osx.hpp
@@ -86,7 +86,10 @@
    * @return True if the key exists, otherwise false.
    */
   virtual bool
-  doesKeyExistInTpm(const Name& keyName, KeyClass keyClass);  
+  doesKeyExistInTpm(const Name& keyName, KeyClass keyClass); 
+
+  virtual bool
+  generateRandomBlock(uint8_t* res, size_t size); 
 
 
   ////////////////////////////////////////////////////////////////////////////////////
@@ -117,7 +120,7 @@
 
  private:
   class Impl;
-  std::auto_ptr<Impl> m_impl;
+  shared_ptr<Impl> m_impl;
 };
   
 } // namespace ndn